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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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23rd May 2019, 8:48 pm | #1 |
Octode
Join Date: Dec 2010
Location: St Ives, Cambridgeshire, UK.
Posts: 1,180
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Farnell power supply electrolytics
Could I recommend to owners of Farnell L series bench power supplies that they check under the bonnet This is a 1972/73 L30DT I picked up recently and the second one I've seen like this. All four cans have vented and two were that bad they've sprayed the rear panel in electrolyte. Very nice units to service anyway, with the exception of the rivets holding the capacitor can clamps in place.
Andrew
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23rd May 2019, 9:05 pm | #2 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,536
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Re: Farnell power supply electrolytics
The wiring layout to the big cans looks dodgy- common in/out wiring resistance in the ripple loop seems to be the case. Probably not noticeable with a decent regulator downstream but still.......
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23rd May 2019, 9:09 pm | #3 |
Octode
Join Date: Dec 2010
Location: St Ives, Cambridgeshire, UK.
Posts: 1,180
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Re: Farnell power supply electrolytics
Hi Chris,
That's the way they come Andrew
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23rd May 2019, 11:09 pm | #4 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,554
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Re: Farnell power supply electrolytics
I caught a set of the high ripple version in something else just before the electrolyte began to seep out.
Several thick coats of varnish over the rubber bungs appears to have worked. Once some electrolyte has got out it is unlikely they will recover. I tried re-hydrating one and found that the rubber had gone so far that it was conductive. The trial was done on a 450V capacitor. Lower voltage types might fare better. |
23rd May 2019, 11:49 pm | #5 |
Dekatron
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
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Re: Farnell power supply electrolytics
Those are nasty. I had a couple of those ruin the power supply in a Telequipment scope. Lose 'em quick.
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24th May 2019, 9:45 am | #6 |
Octode
Join Date: Dec 2010
Location: St Ives, Cambridgeshire, UK.
Posts: 1,180
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Re: Farnell power supply electrolytics
Yes very nasty! There must have been quite some pressure building up in them. Interesting to see how they have vented, the two on the right seem to have been bubbling and sputtering away while the two on the left look like they have completely discharged their liquid contents in one go.
I guess, like many of these units coming out of scientific (as this one has) or educational establishments, it's seen a bit of use. As I say, this is the second one I've seen with vented capacitors in. Anyway, the current incumbents are in process of being ejected and replaced, hence me having to drill out the can clamp rivets to put new 30mm clamps in. Andrew
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25th May 2019, 10:55 am | #7 |
Pentode
Join Date: Apr 2017
Location: South Coast, Western Australia.
Posts: 129
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Re: Farnell power supply electrolytics
My unit has the big 'terry' clips, and I think I posted on here before that the clips were held down with pop rivets. These were too long, had been inserted from underneath, and one had pierced the blue plastic film causing the right channel floating -ve connection to be clamped to ground. I had it for decades before this caused a problem one day.
BC |
26th May 2019, 7:39 pm | #8 |
Octode
Join Date: Jan 2012
Location: Wimbledon, London, UK.
Posts: 1,465
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Re: Farnell power supply electrolytics
I have two of these Farnell PSUs; a single L30B (30VDC, 1A: S/N 002268) and a dual L30DT (two 30VDC, 2A: S/N 000841). I have checked them and the capacitors are fine. The question is, are mine younger or older than the ones with the leaking capacitors?
Colin. |